Mathematical myocardium elasticity properties modeling in echocardiography study of diastolic and systolic function of the left ventricle (Preprint)

BACKGROUND A systematic and quantitative comparative analysis for this subject has not been done so far. Thus defined, the coefficient of elasticity is a whole new dimension. OBJECTIVE This study proposes a new mathematical myocardium elasticity property modeling in characterizing of the ventricular diastole and systole. METHODS The study group consisted of 2283 consecutive patients evaluated by echocardiography. The mathematical approach is made starting from energetic consideration, by applying the energy conservation low for the blood entering from left atrium into left ventricle during diastole period. RESULTS Analyzing all the data obtained we developed two brand new coefficients to describe the cardiac cycle and we had verified if the coefficients are correlated with classically used parameters. We consider that the energetic approach take into consideration the whole mechanical movement that is happening inside the heart and can offer a very synthetic and scientific solid view about the cardiac cycle. CONCLUSIONS The new coefficients are simply to be calculated and as you will see from our research the correlation with other classically used parameters is obvious. The direct physical approach of blood flow within the heart can generate new, beneficial perspectives in diagnosing various heart conditions, or even in understanding how works the filling of the ventricles and atria during a heartbeat.

Topology Optimization of Micro-Structured Materials Featured with the Specific Mechanical Properties

Micro-structured materials consisting of an array of microstructures are engineered to provide the specific material properties. This present work investigates the design of cellular materials under the framework of level set, so as to optimize the topologies and shapes of these porous material microstructures. Firstly, the energy-based homogenization method (EBHM) is applied to evaluate the material effective properties based on the topology of the material cell, where the effective elasticity property is evaluated by the average stress and strain theorems. Secondly, a parametric level set method (PLSM) is employed to optimize the microstructural topology until the specific mechanical properties can be achieved, including the maximum bulk modulus, the maximum shear modulus and their combinations, as well as the negative Poisson’s ratio (NPR). The complicated topological shape optimization of the material microstructure has been equivalent to evolve the sizes of the expansion coefficients in the interpolation of the level set function. Finally, several numerical examples are fully discussed to demonstrate the effectiveness of the developed method. A series of new and interesting material cells with the specific mechanical properties can be found.

Dynamic Characteristics and Restraint Mechanism of Elastically Restrained Connecting Joints on the Flexible Robotic Manipulator

Connecting joints are significant components in mechanical systems as well as the Cartesian flexible robotic manipulator (FRM) which consists of a flexible arm and a moving base through connecting joints. Uncertain factors, such as unqualified assembly, accidental collision, and longtime service, will reduce the restraint stiffness of the connecting joints and enhance the dynamic nonlinearity of the system subsequently. In this case, the traditional perfectly fixed restrained model cannot reflect the real property of the connecting joints. This paper focuses on the elasticity property of the connecting joints with uncertain restraint stiffness, which is defined as the elastically restrained connecting joints (ERCJ), and investigates the dynamic characteristics and restraint mechanism of the ERCJ. An elastic restrained model is proposed to describe the elasticity property of the connecting joints and determine the elastic restrained region of the ERCJ, and the frequency relationship equation in the elastic restrained region is simultaneously determined and verified. Based on the proposed elastic restrained model and Hamilton’s variational principle, the dynamic model and vibration displacement equation of the FRM with elastically restrained connecting joints (FRMERCJ) are established. The virtual prototype experiment of the FRMERCJ is conducted to verify the dynamic model and reveal the restraint mechanism of the ERCJ. The proposed elastic restrained model in this paper can accurately describe the elasticity property of the connecting joints, and the ERCJ is sensitive to motion velocities especially under higher velocities for higher-order vibrations in the initial stage. The results are meaningful for the dynamic analysis and vibration control of robotic manipulators.

Pressure Comfort Research of Women's Wool Underwear

The objective of this study was to investigate the relationship between fabric property and clothing pressure of knitted underwear, using objective pressure evaluates method. Three kinds of fabric for knitted underwear were tested on the thickness, stretching property and elasticity property, and then three same style of underwear which were made by three kinds of fabric were tried on by pressure dummy. Clothing pressure of three different points was measured and recorded. The linear relationship between fabric property and clothing pressure of knitted underwear was obtained. Results show that Clothing Pressure of knitted underwear is negative correlation with elastic recovery rate of knitted fabric.

A Study of the Relationship between Fabric Property and Clothing Pressure of Knitted Underwear

The objective of this study was to investigate the relationship between fabric property and Clothing Pressure of knitted underwear, using objective pressure evaluates method. Eight kinds of fabric for knitted underwear were tested on the stretching property and elasticity property, and then eight same style of underwear which were made by Eight kinds of fabric were tried on by pressure dummy. Clothing pressure of seven different points was measured and recorded. The linear relationship between fabric property and Clothing Pressure of knitted underwear was obtained. Results showed that Clothing Pressure of knitted underwear was negative correlation with elastic recovery rate of knitted fabric, and was positive correlation with tensile stretch rate.

Preparation and Property of Bamboo Silk Fabric

In this paper, natural bamboo yarn and silkworm silk, bamboo pulp yarn and silkworm silk were twisted together to make bamboo silk yarn. And then they were weaved to bamboo silk fabric. The properties of bamboo silk fabrics were studied too. The results showed that bamboo pulp silk fabric was very soft, suitable to make underwear and shirt etc. Natural bamboo silk fabric was relative stiff, suitable to make outwear. All the bamboo silk fabric had wonderful anti statistic property; their cockle elasticity property was equal to silk; the whiteness, moisture regain and moisture permeability were very good. These showed the bamboo silk fabric not only had the properties of bamboo fibers, but also had the properties of pure silk fabric. Then they were suitable to be fabric of garments.

Analysis for Composite Material in Plate-Cone Reticulated Shell

Plate-cone reticulated shell is a new type of space structures with good mechanical behavior and technical economy. Composite material plate is light and strength is high, its ratio intensity is higher a lot than steel material, and elasticity property can be designed, so composite material plate specially applies to prefabricated cone unit of plate-cone reticulated shell. In this paper, GRP plate is regarded as linear elastic material from a view to the engineering application, the multi-layer plate element stiffness matrix is derived with the classic theory of plate and shell, and the GRP plate is designed with equivalent method. Furthermore, the static characteristics for plate-cone reticulated shell with composite material plates are also analyzed in the paper. It is proved by the study that plate-cone reticulated shell with composite material plates is more advantageous and has wide application foreground.